Tensiometer control system



y 1941- w. s. COOK 2,240,637

TENSIOMETER CONTROL SYSTEM Filed July 28, 1938 2 Sheets-Sheet 1 WITNESSES:

INVENTOR M y 9 1941- w. G. cooK TENSIOMETER CONTROL SYSTEM Filed July 2a, 1938 2 Sheets-Sheet 2 WITNESSES:

INVENTOR Patented May 6, 1941 rcssromsrau CONTROL SYSTEM Willard G. 0001:, W kinsburg, Pa.,

Westin Pm! East Pittsburgh,

Penney! assignor to ghouse Electric & Manufacturing Com Pa, a. corporation of Application no as, was, Serial No. emote (oi. comes) Mi malaise e steel as SSvElli through a roll lilii.

m patent application serial iconav one September 23, it have a te sion control system in which tension is applied a strip of material as it passes between adiaceut roll stands, by a tensioning roller applying a transverse deflecting force to the strip; The de flection of the strip is maintained within prede termined limits by controlling the speed of one of the roll stand motors, preferably the'motor or the leading stand, by means of a vibrating regulator which is controlled, through a synchro tie system, in accordance with the position or the tensioning roller,

Que object of my invention is to provide for simplifying the above described tensiometer control system. and improve its operation by eliminating the vibratory regulator, synchro-tie system, and other auxiliary relay devices and substituting apparatus therefor which is of more simple construction.

Another object of my invention is to provide a tension control system for a strip rolling mill which has a minimum of operating parts, which is simple in operation, and which is inexpensive to manufacture, install and maintain.

These and other objects and advantages or my invention will be apparent from the following detailed description taken in connection with the accompanying drawdngs, in which:

Figure l is a diagrammatic illustration of a tension control system embodying the principal features of my invention; and

Figs. 2 and 3 are diagrammatic views of modificaltions of that part of the control system shown in Fig. l which provides the proper energization for the booster generator.

In practicing my invention, I provide for controlling the excitation and speed 01' the leading roll stand motor by means of a booster generator connected in the field circuit of the motor and varying the excitation and voltage oi the booster generator in accordance with the direction and amount of deflection of the strip from a predeterminedposltion. Alternative systems are provided for properly varying the booster generator excitation, using different forms of variable ratio transformers.

Referring now to Fig. 1 of the drawings, I have shown a tensioning device It for acting on a strip of material l2, such as steel strip, to deflect the strip from its normal pass line, and to thus tensicn the strip as passes in the direction by arrow between adjacent roll stands it and i8 of a tandem rolling In order to maintain the amount oi? deflection of 98 from normal pass line within predetermined regulating device it is providedi'or controlling the speed of the driving motor oi the loading roll stand it in response to the flection of the strip iii.

The tensicning device it comprises an idling or tension roller 22 supported by an arm 24 of a bell crank 25 havinga pivotal support 26. The bell crank 25 has a horizontally extending arm 28 which is acted upon by a piston to operating in a cylinder 32. A predetermined fluid pressure is maintained on the piston 3c in the cylinder 32 by means of an automatic fluid pressure regulating valve 34 which is connected between the pressure reservoir shown and the piston 32. The operation of the tensioning device Ill to maintain a substantially predetermined constant tension on the strip I2 is explained in detail in the copending application of G. P. Lessmann, Serial No. 133,419, filed March 27, 1937, now Patent No. 2,189,609, issued February 6, 1940.

In this instance theregulator m may include a variable ratio transformer 36 having aprlmary winding 38 and a secondary winding 40. The primary winding 38 is mounted for rotation relative to the secondary winding 40, the angular displacement of the primary winding 38 with respect to the secondary winding determining the ratio degree of deof transformation 01 the transformer 38, and thus determining the electromotive iorce induced in the secondary winding 40. The primary winding 38 may be rotated by a mechanism which includes a rack 42 connected to the arm 28 of the bell crank 25 so that the motion of the arm 28 will be transmitted to the rack 42. The rack 42 engagesa pinion 44 to rotate the primary winding 38 through a shaft nects the pinion 44 with the' primary winding 38. Thus the primary winding'38 of the transformer 36 is rotated in accordance with the displacement of the strip 12 by the idling roller 22 and the potential induced in the secondary winding Id of the transformer 36 depends upon the degree of displacement of the strip I 2 by the idling roller 22.

The primary and secondary windings 38 and 40 are so adjusted with respect to the operating mechanism 01. the tensloning device III as to have a relative displacement of approximately 45 elec trical degrees when the strip I2 is displaced by the tensiometer ill the desired normal amount.

46 which mechanically con-- Thus, when the deflection of the strip [2 increases above the desired noimal amount, the angular displacement of the primarywinding I! with respect to the secondary winding 48 will be increased, and this will result in a decrease in the potential induced in the secondary winding 10. In a like manner. the potential induced in the secondary winding II will be increased when the displacement of the strip IO decreases from the desired normal amount.

The secondary winding ll of the transformer I! is connected in series circuit relation with a rectifier 4!, the secondary windings I8 and 52 of transformers I4 and II respectively, and the field winding II of a booster generator 80. By this connection it will be seen that the excitation of the booster generator. II will varywith the amount of deflection oi the strip I! from the pass line of the mill.

The booster generator 08 may be continuously driven by a motor 2. The armature of the booster generator 80 is connected in series circuit relation with the iield winding ll of the mill motor 20, a rheostat I! and any source of energization for the fleld winding ll represented by the conductors A and B. The booster generator is so connected in this series circuit as to normally add its potential to the potential oi the source A-B so that the energization of the field winding 64 oi the motor 2| depends upon the sum the potentials o! the source 01' energization A-B and the booster. generator Sill The rheostat I is provided for adjusting the normal energizetlon of the i'ieldwinding N of the mill motor Iii.

The transformer 54 hereinbeiore referred to has a primary winding ll which is connected in accuser tion of the booster generator 50 as to oppose the change in the current flow in the armature oi the motor 20 and to oppose the change in the voltage output of the booster generator 8|). Thus there is provided an anticipating system which will prevent the booster generator 60 from causing too sudden and too great changes in the speed of motor 20 in response to changes in deflection oi the strip [2.

In the operation of the tension regulating system of Fig. 1, the tensioning device ill will function as hereinbeiore described to maintain a predetermined tension on the strip 12 by deflecting the strip from its normal pass line as it passes between the roll stands El and ii. If for any reason the strip should be deflected by the tensioning device it] beyond a desired normal amount, the movement oi. the tensloning device will rotate the primary winding 33 with respect to the secondary winding Ml oi the transformer 36 in the clockwise direction to decrease the Dotential induced in the secondary winding ll. The decrease in the potential induced in the secondary winding ill will decrease the excitation of the booster generator in and this, in turn, will decrease the excitation oi the motor M, with the decrease in excitation of the motor til, the motor will tend to increase its speed and this increase in speed will act through the rolls of series circuit relation with the rheostat l8 and in shunt circuit relation with the interpole windin: II of the mill motor 20. With this connection sudden increases or decreases in the armature current or the mill motor 2! will cause changes in the energization o! the primary winding II. which will induce impulses in the secondary winding II which will be proportional to the magnitude and duration or the changes in the current flow in the armature oi the motor Iii In a similar manner, the primary winding 53 of transformer ll is ccmiected inseries circuit relation with a rheostat 12 and this series circuit is in turn connected in parallel circuit relation with the armature of the booster generator in.

Thus; any change in the output potential oi the booster generator 80 will cause a chance in the onergization oi the primary "winding I3u which in turn will induce an impulse in the secondary winding I! the magnitude and duration of which "will depend upon the magnitude and duration oi the change of the potential cutout of the boooter generator 80. The rheostate BB and -12 are provided to re ulate the current flow in the primary windings II and 53 respectively, to secure the desired functioning oi the transformers ill and to.

The secondary windings and 52 o! the trend formers II and I6, respectively. being connected in series circuit relation with the field windina ll 01' the booster generator 80, will cause chang s in the excitation of the booster generator in when impulses are induced in them. A decreein the potential output or booster generator Bil will cause a decrease in the excitation of the motor 2! and will thus cause an increase in the current flow in the armature of motor 20. The transformers II and 5B are so connected with respect to the interpole winding 10 and the booster generator '0 as to so change the excitareason the deflection oi t the deflection of the utrlp it,

roll stand it to take up the strip i2 between the roll stands It and i5 and thus decrease the amount of deflection of the strip II from the pass line and return this strip to its desired deflected position.

In order'that the regulator it may not eil'ect too great a decrease in the deflection of the strip and thus necessitate that. the deflection be increased again, the anticipating system, comprising transformers El and 5B which act upon the field winding 58 ct booster generator MI in response to changes in the current flow in the armature oi motor iii and potential output of the booster generator M, is provided to counternot the change in the potential output or the booster generator BU, as herclnlleioro explained in detail.

In a like manner, the regulator it will tuneol the strip i! by the to" increase the deflection oi the strip i 1 creasing the speed of the motor xiii M i r any 32 id de crease below the dosh-cal an the anticipating liy'stffilll a'l ecribed hereinhefore urc trom eflecting too great a in 2 oi the trawl modification of that l l: in Fig. l "which "has; to do potential applied to the field "w hoosber generator 6!) in mcpouso to changes in Like ruicre ,e charactc :5 refer to the corresponding elements in Figs. 1 and 2 and the elements oi Fig. 2 may be substituted for the corresponding elements of Fig 1 to produce a completely operative system employing the modification oi the invention shown inFig. 2.

The variable ratio transformer of the embodiment of the invention shcwnln Pig 2 may take the form oi. an auto-transformer H connected to a suitable source of alternating current, designated by conductors a: and y, and having a plurality of voltage taps connected to stationary contact elements it which may be traversed by a has to minimum of operating parts, which is movable contact element 18 which is actuated by the rack 42 through the pinion 44 in accordance with the movements of the idling roller 22. The rock 42 is connected, as hereinbefore described-in connection with the embodiment of the invention shown in Fig. l, to the arm 28 of the bell crank 25 so that variations in deflection of the strip M will move the contact element 78 over the stationary contact elements 18 to change the ratio of transformation of the transformer 74, and thereby control the excitation of the booster generator to,

Lee emhoelirnent of the invention illustrated in 2 will, iunction the manner described in in connection with the emhooiiment oi n Lori shown i with the retio oi? trees by the movohle contact resins the stationary contest ole- M scion changed events or the excitation etoi Gil cleoenuing upon the 1 n oi mo ct the movable contact icon:

c orrce-l zosition shown in "he of u i or i l of the canto- Slim int 32., The &2 core 86 so w ch may iriovecl a vertical direction. by 88 which the invention she tsensiormee i I is c miecteti to 253 or the tech erect: y the yeluctsuce the as Q 3r secondary iii.

- evil; opposite the o co l i ie Vi'fective po-teritrl ix'iildiilg of between the geo'tem:

the output pctenti 1:, this eiiahgcmc ct variable io trensio "1e eiriho cnents oi the invention gs. 2 3 :oectiveiv, he erpctentisi in their second on to inceee e ch. civcuits when the :ieflection oi the strio my of the source oithe cc-octet it wiii iiec Ci sees, omit to decrease the octentiel when the ciefiection decreases. Thus, the soeesi of '7 the roll motor will increase with increesm ti iiectlon of strip anti decrease with clecreeses the deflection of the strip since increases and decreases of the strip will cause decreases and increases, respectively, in the excitation of the roll motes 23.

it will he seen that I have provided tension inc control system for e strip rolling mill which simple and efilcient in operation, and which is inexpensive to manufacture. install and maintain.

In compliance with the requirements of the patent statutes I have shown and described herein the preferred embodiments of my invention. It is to be understood, however, that the invention is not limited to the precise constructions shown and described but is capable of modification by one skilled in the art, the embodiments herein shown being merely illustrative of the principles of my invention.

I claim as my invention:

1. In s, system for maintaining tension on aleneth of materiel es it passes between two work devices, tensionihg means hearing on. the moterioi between the work devices and subjecting the materiel to a, transverse force to thus deflect and tension the material, e variable speed motor con necteci to drive one of the Work devices, a generetcr, circuit means connecting said generator to control the excitation of said motor m ac corconce with the output potential of the generetor, to continuously energized variable ratio transformer, mesons controlled by the degree of efiectioro. of the material from o, predetermined. position for vowels the ratio of said tron former, means for rectifying the output 0:? said transformer, one electrical circuit means connecting the field winding or said generator to be directly; energized iov the rectified output current of soici tvousforiner.

2. In o for controlling the tension on s length of motorist as it posses between two wori'i devices, terisionin-g moons hearing on the mate rial between Wort: devices and subjecting the materiel to nsvei'se force "to thus deflect and tension the moterloi, c, verieble speed motor cornnecte-si drive one of the work devices, a gen erotor connecteti to control excitation of soioi tor, e continuously energized variable ratio ousforvoei', moons controlled by the degree or deflection oi from a predetermined position for varying; the ratio of said trons former, cectifier, at second and 2 third trons Emmet, circuit means connecting said rectifier, the minding of solid generator and one windeach of soio second third transformers circuit with the secondary winding of said vorieicle ratio transformer, circuit co=r1= nesting-r the other vnineing of said second transto he energized in accordance with the moisture of seicl motor, and circuit connecting" the other whistles of ssiol simmer to he energized in accordance with zeotezitisl of said genera-tor.

e, contioi system for restricting the speed of motor in accordance with the movement of c movable element, continuously driven genes etor, circuit moons connecting said generator to excite the motor in accordance with output potential. eoiol generator, at variable ratio trans to oer, means for varying the ratio of said trsnsformer in sccorc'ience with the degree of move merit of the move-hie element, a, rectifier, anti electrical circuit means connecting said rectifier cool the field winding of said genera/tor directly in electrical circuit with the secondary winding of seici vcvielole ratio transformer.

4. in control system for regulating the speed or" o motor in accordance with the movement oi o movohle element, o continuously driven gamerrotor connected to affect the excitation of the motor in accordance with. the output potential of said generator, a, variable ratio transformer,

means for varying the ratio said transformer in accordance with the degree of movement of the movable element, a rectifier, a second and a third transformer, circuit means connecting one winding of said second transformer to be energlued in accordance with the armature current of the motor, circuit means connecting one winding of said third transformer to be energized in acoordance with ator, and circuit means connecting the other winding of said second and third transformers, said rectifier and the field winding of said generator in circuit with the secondary winding of said variable ratio transformer.

5. In a tandem strip rolling mill, tensioning means bearing upon the strip as it passes between adjacent roll stands of the mill subjecting the strip to a transverse force to thus deflect and tension the strip, a variable speed motor connected in driving relation with the rolls of one of the adjacent roll stands, a continuously driven generator connected to affect the excitation oi said motor in accordance with the output peters tial of said generator, a transformer having its primary and secondary windings relatively mow able to vary the transformer ratio, means controlled in accordance with the deflection oi the strip by said tensioning means for producing relative movement of said transformer windings, a rectifier, and electrical circuit means directly connecting the secondary of said transformer, said rectifier and the field winding of said generator in series circuit relation.

6. In a tandem strip rolling mill, tensionlng means bearing on the strip as it passes between adjacent roll stands of the mill subjecting the strip to a transverse force to thus deflect and tension the strip, a variable speed motor conthe output potential of said genernected in driving relation with the rolls of one I of the adjacent roll stands, a continuously driven generator connected to control the excitation of said motor in accordance with the output potential of said generator, a transformer having a core of variable reluctance, means controlled in accordance with the deflection of the strip for varying the reluctance of said transformer core, a rectifier, and electrical circuit means directly connecting the secondary 01' said transformer, said rectifier and the field winding oi said generator in series circuit relation.

I. In a device for maintaining tension on a length of material as it passes between two work devices, tensionlng means bearing on the length of material between the work devices and sub iecting the material to a transverse force to thus deflect and tension the material, a'variable speed motor connected to drive one of the work devices, a continuously driven generator connected to excite said motor, an auto-transformer having a series of taps intermediate the ends of its windings, a movable contact element for selectively engaging said taps, means for moving said contact element in accordance with the deflection of the material, a rectifier, and circuit means connecting said rectifier, the field winding of said generator, one end of said transformer windings and said movable contact element directly in scrim electrical circuit relation.

8. In a tandem strip rolling mill, tensioning means bearing upon the strip as it passes between adjacent roll stands 01 the mill subjecting the strip to a transverse force to thus deflect and tension the strip, a variable speed motor connected in driv g relation with the rolls 0! one of the adjacent in stands, a continuously driven generator connected to excite said motor, a first transformer having its primary and secondary windings relatively movable to vary the transiormer ratio, means controlled in accordance with thevdefiection of the strip by said tension-- cult relation,

9, In a tandem strip rollito i, ii, tensiomng means bearing on the strip as it n so hctween adjacent roll stands of the rub], ting the strip to a transverse force to tlziua lieiliect and tension the strip, a variable tweed motor comnected in driving relation with the rolls or one of the adjacent roll stands, a continuously driven generator connected to excite said motor, a first transformer having a core of variable reluctance. means controlled in accordance with the deflection of the strip ior varying the reluctance of said transformer core, a rectifier, a second transformer having its primary winding connected to be energized in accordance with the armature current of said motor, a third transformer having its primary winding connected to be energized in accordance with the output potential oi said generator, and circuit means connecting the secondary windings of said first, second and third transformers, said rectifier and the field winding of said generator in series circuit relation.

10. In a device for maintaining tension on a length of material as it passes between two work devices, tensloning means bearing on the length of material between the work devices and subjecthaving its primary winding connected to be encrglzed in accordance with the armature current of said motor, a third transformer having its primary winding connected to be energized in accordance with the output potential 0! said generator, and circuit means connecting said rectiher, the secondary windings of said second and third transformers, the field winding of said generator, said movable contact element and an end of the winding of said auto-transformer in series circuit relation.

WILLARD G. COOK. 

